Gaping crevasses that penetrate upward from the bottom of the largest remaining ice shelf on the Antarctic Peninsula make it more susceptible to collapse, according to University of Colorado Boulder researchers who spent the last four Southern Hemisphere summers studying the massive floating sheet of ice that covers an area twice the size of Massachusetts.

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But the scientists also found that ribbons running through the Larsen C Ice Shelf — made up of a mixture of ice types that, together, are more prone to bending than breaking — make the shelf more resilient than it otherwise would be.

The research team from CU-Boulder’s Cooperative Institute for Research in the Environmental Sciences presented the findings Dec. 6 at the American Geophysical Union’s annual meeting in San Francisco.

The Larsen C Ice Shelf is all that’s left of a series of ice shelves that once clung to the eastern edge of the Antarctic Peninsula and stretched into the Weddell Sea. When the other shelves disintegrated abruptly — including Larsen A in January 1995 and Larsen B in February 2002 — scientists were surprised by the speed of the breakup.

Researchers now believe that the catastrophic collapses of Larsen A and B were caused, at least in part, by rising temperatures in the region, where warming is increasing at six times the global average. The Antarctic Peninsula warmed 4.5 degrees Fahrenheit since the middle of the last century.

The warmer climate increased meltwater production, allowing more liquid to pool on top of the ice shelves. The water then drained into surface crevasses, wedging them open and cracking the shelf into individual icebergs, which resulted in rapid disintegration.

But while the meltwater may have been responsible for dealing the final blow to the shelves, researchers did not have the opportunity to study how the structure of the Larsen A and B shelves may have made them more vulnerable to drastic breakups — or protected the shelves from an even earlier demise.